Author: Uri Blass
Date: 08:10:53 10/19/00
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On October 19, 2000 at 09:18:45, Dieter Buerssner wrote: >On October 18, 2000 at 14:14:20, Uri Blass wrote: > >>I can give another rule: >>Blacks draw if it is black to move and the distance between the black king and >>the corner in king moves is smaller than the ditance between the corner and the >>white pieces except the bishop(white king in king moves and white pawn in pawn >>moves) >> >>If it is white to move then use distance-1 instead of distance for white. > >Uri, thank you very much, for giving your rule. Also thanks to all >the other answers to my questions. > >I have made a small experiment. I set up 10000 random positions >with a white pawn on h, the wrong bishop and the kings on two random >legal squares. Black to move. >Of the 10000 positions, 3716 where draws due to TBs. >I compared the result of your rule, and the result that is returned by TBs. Your >rule had an overall success rate of 90%. >At first sight, this might not look too good, but it will probably be >very good in practical play. I checked some of the positions, where the >"rule" failed. Most positions, where you rule failed, where when it predicted >a loss and the position is draw are trivial, because the Black king can capture >the pawn in the next move. So in a real game, the quiescence search would find >this immediately. > >In a few cases, the pawn can be captured the move after the next move, >and these are of course more dangerous. One example > >[D] 2B5/8/7P/5k2/8/8/3K4/8 b - - 0 0 > >But again here, with the help of search, this will be found soon. > >Rarely, your rule predicted a draw, when the position is lost. But here the >success rate of your rule was almost 99%. (In 95 positions, your rule predicted >a wrong draw). One example: > >[D] 5k2/8/7P/8/8/8/B7/6K1 b - - 0 0 No my rule does not say that it is a draw because the distance of the king to the corner is equal and not smaller then the distance of the pawn. I guess that in most of the cases when the distance is equal it is a draw but my rule was made to be always correct when it says draw. It is possible to do a rule that is 100% correct when it says win when the other positions can be divided to probably draw and probably win for white but I did not do it. Uri
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